temperature difference

[DeliMB]

Hi,

I constantly get temperatures from a sensor and I want to build the temperatures difference from the start temperature and each other temperature. The Problem is that my Sub VI is in a Main VI with a while loop so the 0 index of the array (with the temperatures) is not always the same. How can I save and use the very first start temperature T0? 

[GerdW]

Hi Deli,

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@DeliMB wrote:

so the 0 index of the array (with the temperatures) is not always the same. 

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The index "0" of an array will always be the index "0"…

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@DeliMB wrote:

How can I save and use the very first start temperature T0? 

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Use a shift register for T0…

[DeliMB]

First of all thank you for your fast answer. 

Then why do I get every second another Element. My Indicator changes constantly.

And I cannot use a shift register because I work in a Sub VI and I am not able to use the Main VI.

[GerdW]

Hi deli,

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@DeliMB wrote:

Then why do I get every second another Element. My Indicator changes constantly.

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Because with each iteration you create a new array made of one single random number...

What else do you expect from your code???

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@DeliMB wrote:

And I cannot use a shift register because I work in a Sub VI and I am not able to use the Main VI.

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You can use shift registers in your mainVI as well as in the subVI. When you don't know this I recommend the beginner tutorials offered at the top of the LabVIEW board!

Hint: Examine the point-by-point functions to learn about (one way of) using shift registers...

[DeliMB]

Yes Sir that was my Point. i Need the very first Element of the very first Array. 

I will try it with the Shift Register. 


thanks a lot Mister Gerd! 

[Mark_Yedinak]

Your code is senseless. Your loop is building a new array every iteration using a random number wired to all elements of the array. Your indicator called appended array is never an appended array. It will always be a three element array containing the exact same random value in each element.

I highly recommend that you go through the tutorials linked at the top of the forums page.

[DeliMB]

I Know that this is senseless. I just want do Show my Problem as you can See there is Not a Input of a Temperature sensor. 
i just wanted to Know how I can Save and use the First Element of my array. I Need the temperature T0 and thats my Point. (I thought it should be the index 0 But this doesn‘t work in a while Loop)

I Hope someone understands me. 

[DeliMB]

I Know that. I just want to explain my problem. As you can See there isn‘t any temperature inputs. That’s Just a VI that I Made to show my problem.
I want to Save and use the First Element of the First Array (everything Happens in a while Loop), Thats the start temperature T0. So I can calculate the temperature difference between the First and each other Element. 

I Hope someone understands me now. 

[GerdW · Accepted solution]

Hi Deli,

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@DeliMB wrote:

I want to Save and use the First Element of the First Array (everything Happens in a while Loop), Thats the start temperature T0. So I can calculate the temperature difference between the First and each other Element.

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Store the first element of the array to a shift register - but only in the first iteration of your loop!

You need a shift register and a case structure (or Select node)…

Or you measure T0 before your loop and just use a wire to feed it into the loop.

Or you build a statemachine with one state of "measure T0" and other states like "measure new values". Then use shift registers again…

Or…